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ABSTRACT Arrayed mutant libraries are important resources that have advanced our understanding of bacterial genetics. Until recently, essential genes which are necessary for bacterial survival, and constitute ~10% of bacterial genes, were not included in arrayed library resources. However, recent advances in clustered regularly interspaced short palindromic repeats interference (CRISPRi) have made it possible to study essential genes with increasing throughput. Here, we constructed an arrayed CRISPRi library in the dental caries pathogen Streptococcus mutans, known as SNAP ( S treptococcus mutans arrayed CRISPRi). In this library, each strain contains a short guide RNA which selectively targets a single essential gene, and this is controlled through xylose induction. In total, the library can selectively repress >250 essential and growth-supporting genes. Initial characterization showed that SNAP strains grow as expected, and initial proof-of-concept experiments displayed the utility of the library. We anticipate that this library will be of benefit to the research community by allowing for high-throughput characterization of S. mutans essential genes. IMPORTANCE The construction of arrayed mutant libraries has advanced the field of bacterial genetics by allowing researchers to more efficiently study the exact function and importance of encoded genes. In this study, we constructed an arrayed clustered regularly interspaced short palindromic repeats interference (CRISPRi) library, known as S treptococcus mutans arrayed CRISPRi (SNAP), as a resource to study >250 essential and growth-supporting genes in Streptococcus mutans. SNAP will be made available to the research community, and we anticipate that its distribution will lead to high-quality, high-throughput, and reproducible studies of essential genes.

Industrial application of hydrophobic materials is numerous particularly as adsorption beads to remove organic pollutants. In this research combined effect of hydrophobicity and reactive epoxide group on the adsorption behavior of dye molecules by composite polymer particles was investigated. Lauryl methacrylate (LMA) a poor water soluble long chain vinyl monomer is commercially available. Polystyrene/poly(LMA-divinyl benzene) or PS/P(LMA-DVB) composite seed particles were first prepared by slightly modified activated swelling of micron-sized PS seed particles utilizing either water or water-ethanol dispersion medium. The influence of poly(vinyl alcohol) (PVA) as steric stabilizer on the size and size distribution was evaluated. The poor solubility of LMA in the continuous phase hindered the homogeneous swelling of PS particles even in the presence of ethanol (5% w/w) and resulted in fairly polydispersed PS/P(LMA-DVB) composite seed particles. The composite seed particles were then functionalized with epoxide group by seeded polymerization of glycidyl methacrylate (GMA) to produce PS/P(LMA-DVB)/PGMA composite polymer particles. The epoxide functionalized PS/P(LMA-DVB)/PGMA composite polymer particles were used to adsorb two kinds of azo dyes, congo red (CR) and direct red-75 (DR-75). The effects of initial dye concentration at 303 and 323 K on adsorption behavior were investigated and the adsorption was explained by adsorption isotherms. Temperature dependent adsorption measurements were also carried out at identical initial dye concentration. The adsorption results showed that inclusion of reactive epoxide group on/near the surface of hydrophobic PS/P(LMA-DVB) composite seed particles improved the adsorption capacity of dye molecules. Keywords: Hydrophobic composite, Epoxide, LMA, Adsorption isotherm, Dye

The discovery of chimeric anti-melanoma agents is reported. These molecules are potent growth suppressors of melanoma cells in vitro with growth inhibition of 50% (GI50) values as low as 1.32 µM. Compounds were more toxic to melanoma cells in vitro than commonly used anti-melanoma agent dacarbazine as measured by TUNEL assay. They induced both caspase-independent apoptosis evident by colocalization of TUNEL with endonuclease G (EndoG) and caspase-mediated apoptosis measured by colocalization of TUNEL with caspase-activated DNase (CAD). In addition, compounds 3 and 5 strongly induced oxidative injury to melanoma cells as measured by TUNEL colocalization with heme oxygenase-1 (HO1). Dacarbazine induced only caspase-independent apoptosis, which may explain why it is less cytotoxic to melanoma cells than compounds 3, 4 and 5.

From a library of compounds, 11 hit antibacterial agents have been identified as potent anti-Gram-positive bacterial agents. These pyrazole derivatives are active against two groups of pathogens, staphylococci and enterococci, with minimum inhibitory concentration (MIC) values as low as 0.78 μg/mL. These potent compounds showed bactericidal action, and some were effective at inhibiting and eradicating Staphylococcus aureus and Enterococcus faecalis biofilms. Real-time biofilm inhibition by the potent compounds was studied, by using Bioscreen C. These lead compounds were also very potent against S. aureus persisters as compared to controls, gentamycin and vancomycin. In multiple passage studies, bacteria developed little resistance to these compounds (no more than 2 × MIC). The plausible mode of action of the lead compounds is the permeabilization of the cell membrane determined by flow cytometry and protein leakage assays. With the detailed antimicrobial studies, both in planktonic and biofilm contexts, some of these potent compounds have the potential for further antimicrobial drug development.

Enterococci and methicillin-resistant S. aureus (MRSA) are among the menacing bacterial pathogens. Novel antibiotics are urgently needed to tackle these antibiotic-resistant bacterial infections. This article reports the design, synthesis, and antimicrobial studies of 30 novel pyrazole derivatives. Most of the synthesized compounds are potent growth inhibitors of planktonic Gram-positive bacteria with minimum inhibitory concertation (MIC) values as low as 0.25 µg/mL. Further studies led to the discovery of several lead compounds, which are bactericidal and potent against MRSA persisters. Compounds 11, 28, and 29 are potent against S. aureus biofilms with minimum biofilm eradication concentration (MBEC) values as low as 1 µg/mL.

Acinetobacter baumannii has emerged as one of the most lethal drug-resistant bacteria in recent years. We report the synthesis and antimicrobial studies of 25 new pyrazole-derived hydrazones. Some of these molecules are potent and specific inhibitors of A. baumannii strains with a minimum inhibitory concentration (MIC) value as low as 0.78 µg/mL. These compounds are non-toxic to mammalian cell lines in in vitro studies. Furthermore, one of the potent molecules has been studied for possible in vivo toxicity in the mouse model and found to be non-toxic based on the effect on 14 physiological blood markers of organ injury.

In this paper, synthesis and antimicrobial studies of 31 novel coumarin-substituted pyrazole derivatives are reported. Some of these compounds have shown potent activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) as low as 3.125 µg/mL. These molecules are equally potent at inhibiting the development of MRSA biofilm and the destruction of preformed biofilm. These results are very significant as MRSA strains have emerged as one of the most menacing pathogens of humans and this bacterium is bypassing HIV in terms of fatality rate.

Microbial resistance to drugs is an unresolved global concern, which is present in every country. Developing new antibiotics is one of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat bacterial resistance to drugs. Based on our lead molecules, we report the synthesis and antimicrobial studies of 27 new pyrazole derivatives. These new coumarin-pyrazole-hydrazone hybrids are readily synthesized from commercially available starting materials and reagents using benign reaction conditions. All the synthesized molecules were tested against 14 Gram-positive and Gram-negative bacterial strains. Several of these molecules have been found to be potent growth inhibitors of several strains of these tested bacteria with minimum inhibitory concentrations as low as 1.56 μg/mL. Furthermore, active molecules are non-toxic in in vitro and in vivo toxicity studies.

Background A zoonotic, double-stranded DNA virus belonging to the genus Orthopoxvirus, the mpox virus (MPXV) is most common in tropical regions of Central and West Africa. The frequency of monkeypox (mpox) cases, however, has sharply climbed globally since May 2022. Objectives To establish the threat of mpox in terms of the oral lesions caused in sufferers. Materials and methods After a thorough study of the literature identified in the PubMed, Web of Science, and Cochrane library databases using the PRISMA framework, 103 papers were found. Using inclusion and exclusion criteria, we chose research that was relevant for our review before shortlisting 14 papers that conformed to the review's guidelines. Results In the 14 selected studies, it was found that oral lesions were among the first clinical signs of a mpox affliction, with ulcers on the dorsal surface of tongue lips being the most common areas affected. Conclusion The rarely observed oral lesions of mpox infection may help in the diagnosis and management of this condition. It is critical to keep in mind that recognising and detecting oral lesions in mpox patients opens the door to more research and efficient patient management.